1. Field of the Invention
The present invention relates generally to electrical power generation and distribution, and more particularly but not exclusively to methods and apparatus for monitoring energy consumption.
2. Description of the Background Art
A solar cell module comprises a plurality of solar cells configured to collect solar radiation for conversion to electrical energy. As the price of oil and the need for renewable power sources continue to increase, so too is the demand for solar cell modules. Solar cell modules may be installed as an additional power source in a customer structure, which may be residential or commercial. For example, a residential home with solar cell modules may continue to receive power from a utility company. For accounting, cost analysis, energy conservation improvement, or other reasons, it is advantageous for the customer (the home owner in this example) to determine how much energy he is receiving from the utility company compared to the solar cell modules. This determination is part of the customer's energy balance, which is the relation between energy consumption and generation. Some solar cell module vendors, such as Sunpower Corporation of San Jose, Calif., incorporate in their solar cell modules mechanisms for readily determining the amount of energy generated by the solar cell module. However, the amount of energy drawn from the utility company is not so easily determined. Although utility companies provide utility meters for manually reading the amount of energy consumed by the customer, utility companies generally do not provide an interface for third parties to electronically access information from the utility meters. This makes it difficult for solar cell module installers, who are essentially in competition with the utility companies, to calculate the customer's energy balance.